The present invention relates generally to the field of underground boring and, more particularly, to a system and method of dispensing a lubricant to threaded joints between a drive spindle of a drilling machine and a drill rod being threaded or unthreaded with respect to the drive spindle.
In accordance with a general horizontal boring technique, also known as microtunnelling, horizontal directional drilling (HDD) or trenchless underground boring, a boring system is situated on the ground surface and drills a hole into the ground at an oblique angle with respect to the ground surface. A drilling fluid is typically flowed through the drill string, over the boring tool, and back up the borehole in order to remove cuttings and dirt. After the boring tool reaches a desired depth, the tool is then directed along a substantially horizontal path to create a horizontal borehole. After the desired length of borehole has been obtained, the tool is then directed upwards to break through to the earth""s surface. A reamer is then attached to the drill string which is pulled back through the borehole, thus reaming out the borehole to a larger diameter. It is common to attach a utility line or other conduit to the reaming tool so that it is dragged through the borehole along with the reamer.
In order to increase the length of the drill string during a boring operation, drill rods are situated in a carriage of the HDD machine and individually threaded onto to the drill string using a spindle or drive chuck powered by a rotation motor of the HDD machine. In order to decrease the drill string length, such as during a backreaming operation, individual drill rods are unthreaded from the drill string and removed from the carriage.
It can be appreciated that the above-described threading and unthreading operations introduce stress and heat into the threaded joint interface between the spindle and drill rod. If sufficient lubricity is not present a3t the threaded joint interface, several undesirable results may occur. For example, excessive heat and friction generated at the threaded joint interface may cause premature wear on the spindle/drive chuck/drill stem. Threads of the spindle and those of a drill rod may bind together due to excessive heat, pressure, and torque. Such binding at the threaded joint interface may create a weld characteristic, thereby limiting the ability to disjoint the rod. The inability to disjoint a rod can ultimately cause failure of the boring operation.
Conventional manual approaches to applying a lubricant, such as grease, to the threaded joint interface are time consuming, labor intensive, cumbersome, and typically unpleasant. Although some degree of automation has recently been proposed, such proposed approaches are fairly crude and fail to take into account operational factors such as ambient and drilling machine temperatures, rate of spindle rotation during threading and unthreading operations, and control of lubricant application rates and volumes.
There exists a need in the excavation industry for an apparatus and methodology for automating the delivery of a lubricant to a threaded joint interface between a spindle and drill rod when making or breaking a threaded joint. There exists a further need for such an apparatus and methodology which optimizes the automatic application of a lubricant to a threaded joint interface. The present invention fulfills these and other needs.
The present invention is directed to a lubrication system for dispensing a lubricant to threads of a drill rod and/or a spindle of a horizontal directional drilling (HDD) machine during a rod loading or unloading operation. A lubrication system of the present invention includes a pumping system having a lubricant reservoir, a pump, an applicator, and a lubricant supply conduit coupled between the pump and applicator. A control unit is coupled to the pumping system. The control unit, in response to an operator signal or an HDD machine control signal, activates the pumping system to dispense a volume of lubricant from the applicator to the threads of the drill rod and/or spindle. The control unit may control the pumping system to dispense the lubricant substantially over a circumferential surface of the threads of the spindle and/or drill rod.
A heating unit may be coupled to the pumping station and heats lubricant contained within the pumping system. A heating unit may, in addition or in the alternative, be coupled to the applicator, in which case the heating unit heats lubricant within the applicator.
The heating unit includes an inlet port and an outlet port. The heating unit receives a thermal transfer fluid from the HDD machine via the inlet port and returns the thermal transfer fluid to the HDD machine via the outlet port. In one embodiment, the heating unit is coupled to a gearbox of the HDD machine. The heating unit receives a thermal transfer fluid from the gearbox via the inlet port and returns the thermal transfer fluid to the gearbox via the outlet port. The heating unit may be controlled by the control unit to vary a viscosity of the lubricant.
In accordance with another embodiment, the heating unit is coupled to an engine coolant system of the HDD machine. The heating unit receives a thermal transfer fluid from the engine coolant system via the inlet port and returns the thermal transfer fluid to the engine coolant system via the outlet port. According to a further embodiment, the heating unit is coupled to a source of electrical power provided on or external to the HDD machine. The heating unit generates heat to heat lubricant within the pumping system in response to a current received from the electrical power source.
The heating unit may further include a first heat transfer unit coupled to the pumping system to heat lubricant within the pumping system and a second heat transfer unit coupled to the applicator to heat lubricant at the applicator. In another embodiment, the heating unit includes a first heat transfer unit coupled to the pumping system to heat lubricant within the pumping system and a third heat transfer unit coupled to the lubricant supply line to heat lubricant within the lubricant supply line.
The pumping system is provided with power supplied by the HDD machine or power source external to the HDD machine. The pumping system may be provided with hydraulic or pneumatic power supplied by the HDD machine. The pumping system may alternatively be provided with electric or mechanical power from the HDD machine. In one embodiment, the pumping system is provided with hydraulic power supplied by one or both of a rotation pump or a displacement pump of the HDD machine.
The pumping system dispenses a fixed volume of lubricant through the applicator according to an embodiment of the invention. The control unit may produce a control signal to vary a rotation rate of the rod and/or spindle, and the pumping system may dispense a fixed volume of lubricant through the applicator at a variable dispensing rate during a time in which the rotation rate of the rod and/or spindle is varied.
In one embodiment, the control unit, in response to a rotation rate of the rod and/or spindle, adjusts one or more characteristics of the pumping system to dispense a desired volume of lubricant to all or selected portions of a thread of the rod and/or spindle. In another embodiment, the control unit controls a duration of dispensing produced by the pumping system during a time in which the spindle and rod are threaded together, such that the dispensing time is proportional to a rotation rate of the spindle and/or rod.
The applicator, according to one embodiment, includes a nozzle. The nozzle may include an orifice that varies in one or both of size or shape. The nozzle has an associated adjustable spray pattern. The control unit may adjust one or both of a cross-sectional width of the spray pattern or a length of the spray pattern. The pumping system may be an airless pumping system.
A cleaning apparatus may further be provided that cleans the threads of the spindle and/or rod. The control unit may disable the pumping system from dispensing lubricant until the cleaning apparatus completes cleaning of the threads of the spindle and/or rod.
The system may further include an indicator, such as a visual, auditory, or tactile indicator, that indicates the state of lubrication system readiness. The control unit activates the indicator to indicate readiness of the lubrication system when the system is enabled for activation.
In accordance with another embodiment of the present invention, a lubrication system includes a pumping system having a lubricant reservoir, a pump, a lubricant transfer collar, a spindle passageway and a lubricant transfer conduit coupled between the pump and collar. The spindle passageway is defined within a portion of the spindle and has an inlet port defined on a surface of the spindle. The pumping system is activated by the rotation of the spindle or another consistently powered machine element such that it is capable of generating a nearly constant pressure in the lubricant transfer conduit. The grease is then pumped at the appropriate time due to the fact that the aperture is blocked when the spindle is threaded to a drill rod, and opens as soon as the threaded joint begins to separate. The lubrication of the joint occurs during the unthreading action in which the aperture in the spindle is rotating relative to the drill rod.
In accordance with another embodiment, a control unit is coupled to the pumping system. The control unit, in response to an operator signal or an HDD machine control signal, activates the pumping system to dispense a volume of lubricant from the aperture to the threads of the spindle and/or drill rod.
The inlet port of the spindle passageway is preferably defined on a surface of the spindle free of threads. The lubricant reservoir and pump are preferably movably or hingedly supported on the HDD machine. The pump includes an outlet that engages the inlet port of the lubricant supply conduit.
The lubricant transfer collar may include a pump collar having an annular sealed channel that encompasses the inlet port of the spindle passageway. The pump includes an outlet that engages the pump collar.
In one embodiment, the pump constitutes a mechanical pump. The pump may include a gearbox that engages the spindle. The pump preferably dispenses lubricant at a rate proportional to a rate of rotation of the spindle when there is no outlet restriction, and subsequently maintains a constant maximum pressure. The pumping system preferably dispenses a fixed volume of lubricant through the aperture, but may alternatively dispense a varying volume of lubricant through the aperture.
The control unit may produce a control signal to vary a rotation rate of the rod and/or spindle. The pumping system may dispense a fixed volume of lubricant through the aperture at a variable dispensing rate during a time in which the rotation rate of the rod and/or spindle is varied or held constant. The control unit may also control a duration of lubricant dispensing by the pumping system during a dispensing time in which the spindle and rod are being threaded together or unthreaded, the dispensing time being proportional to a rotation rate of the spindle and/or rod.
The pumping system may further include an indicator to indicate readiness of the lubrication system. A heating unit may also be coupled to the pumping system.
Another embodiment of the present invention is directed to a method of dispensing a lubricant to threads of a drill rod and/or a spindle of a horizontal directional drilling (HDD) machine during a rod loading or unloading operation. A lubricant dispensing methodology, according to this embodiment, involves rotating the spindle and/or drill rod, and dispensing the lubricant to the threads of the spindle and/or drill rod. The method further involves controlling one of a lubricant dispensing rate or a spindle rotation rate to dispense the lubricant substantially over a circumferential threaded surface of the spindle and/or drill rod.
Dispensing the lubricant may involve dispensing a fixed or varying volume of the lubricant. The lubricant dispensing rate may be controlled as a function of spindle rotation rate. In one embodiment, the rate at which a fixed volume of the lubricant is dispensed is controlled as a function of spindle rotation rate. In another embodiment, the spindle rotation rate is varied to dispense a fixed volume of the lubricant substantially over the circumferential surface of the threads of the spindle and/or drill rod. The lubricant dispensing rate may be controlled as a function of spindle diameter and a preestablished spindle rotation rate.
Dispensing the lubricant, according to this embodiment, may involve spraying the lubricant onto the threads of the spindle and/or the drill rod. In an alternative embodiment, dispensing the lubricant involves communicating the lubricant through a passageway defined within the spindle to one or more apertures defined within the threads of the spindle and/or the drill rod. The lubrication dispensing methodology may also include heating the lubricant. The applicator may constitute a spray applicator, an applicator that contacts the threads, or an aperture defined within a region of the threads which communicates the lubricant to the threads received from a passageway defined within the spindle.
According to a further embodiment, each drill rod is provided with a lubricant supply conduit extending axially along the length of the rod. The axially extending lubricant supply conduit may be a bore defined within a wall of the rod which extends along the length of the rod. The lubricant supply conduit may alternatively be disposed along an inner or outer diameter surface of the rod. One or more apertures are provided within the thread area of the rod which extend to the lubricant supply conduit of the rod. When a rod is threaded onto the spindle, the aperture(s) of the spindle are fluidly coupled to the axially extending lubricant supply conduit of the drill rod. Lubricant is communicated through the spindle aperture, through the spindle/rod fluid interface, and along the length of the drill rod via the lubricant supply conduit of the drill rod.
During a rod unloading operation, the rod-to-rod joint proximate the vice clamping mechanism is broken. As this joint is broken during the unthreading procedure, lubricant is forced into the rod-to-rod threaded interface, which assists in the separating the two rods with minimal heat and mechanical stress. After the rod-to-rod joint is broken, the clamping mechanism clamps the rod thereby temporarily preventing further rod rotation. The spindle-to-rod joint is then broken while being subject to automatic lubrication in a manner previously described. After unthreading the spindle from the rod, the clamping mechanism releases the rod and the rod is removed from the carriage and transferred to the rod magazine.
The above summary of the present invention is not intended to describe each embodiment or every implementation of the present invention. Advantages and attainments, together with a more complete understanding of the invention, will become apparent and appreciated by referring to the following detailed description and claims taken in conjunction with the accompanying drawings.